1. Field of the Invention
The present invention relates to a vehicle stabilizing and leveling system, and in particular to a stabilizer system used with a towed vehicle such as an agricultural harvester.
2. Description of the Prior Art
Agricultural equipment that is generally towed behind a tractor faces challenges to maintain stability while traveling over uneven terrain. With certain types of equipment, maintaining stability is a particular concern due to a higher center of gravity and mass of elevated components while the equipment is moving. In particular, equipment utilized to access fruit from trees causes stability and leveling problems due to elevated engagement assemblies. Some equipment has a moving mast supporting a number of arms that provide relative side-to-side movement at a high center of gravity. In addition, the equipment may be pushed or pulled laterally due to engagement with the trees as it is towed. In extreme cases, the equipment may be subject to tipping over from passing over the uneven terrain and/or movement of the mast and arms to an extended position.
One way to overcome the problem is to lower the center of gravity on the towed vehicle. This is not always possible by reconfiguring the equipment. Adding mass at a lower portion of a harvester may lower the center of gravity, but also increases the weight of the towed vehicle. However, the increased weight makes towing more difficult and requires additional power for the additional weight being towed. Moreover, vehicle weight may be restricted by allowable ground pressure, thereby preventing the use of added mass for some applications.
Other systems have utilized controls to adjust the relative positions of various components on the towed vehicle. Leveling systems include control circuits that move certain elements relative to the frame of the towed vehicle. However, electronic controls may not provide a sufficiently quick response time to correct for irregularities and to counteract tipping. In addition, corrections have not been made proportionally to ensure the correction is also proportional. Therefore, attempts to utilize electronic controls have proven to be unsatisfactory. Improper reaction times with under compensation and overcompensation may lead to oscillation in an unintended manner that worsens the situation, leading to control problems with the towed vehicle.
It can be seen that a new and improved stabilizing system for a towed vehicle is needed. Such a system should provide for simple, reliable correction when the towed vehicle is tilted in an unintended manner. Such a system should also utilize the mass of the towing vehicle without adding weight to the towed vehicle to offset the elevated moving assemblies of the towed vehicle. Such a system should provide for correction while providing sufficient flexure to accommodate the towing vehicle without binding, yet taking advantage of the weight of the towing vehicle. Corrections to the stability of the system should be made in a manner proportional to the degree of tilting from the desired orientation to eliminate unwanted oscillation. The present invention addresses these as well as other problems with stabilizing towed vehicles.